1. Field of the Invention
This invention is related to a power processing system and more particularly to a power controller wherein the power output capacity can be varied by adding or removing individual power output modules.
2. Description of the Prior Art
Prior art servo controllers, power amplifiers, and power regulators are normally designed to provide a given output capacity. Once constructed it is difficult, if not impossible, to increase the output rating of prior art devices without major disassembly or redesign.
In some prior art power controllers, it is necessary to have a feedback signal related to current to provide adequate protection and control of the device. Some prior art devices have output sections configured as a bridge in which the current feedback signal is derived from a shunt disposed in series with the load at the bridge output. This generally provides a signal having poor form factor with little usable information because of the presence of high common-mode voltages at the shunt. It has been discovered and recognized that by placing two sampling resistors, one in each leg of the bridge circuit at the common connection point, a superior current feedback signal can be derived using a differential amplifier.